Research On Optical Component Damage Detection Technology Based On Optical Parametric Amplification

Large laser devices use thousands of optical components,many of which operate at high laser fluxes and are highly susceptible to damage.At present,many countries in the world have carried out research on related technologies for online detection of optical component damage,so as to obtain the damage of components quickly and effectively.On-line detection of damage to optical components of large laser devices typically uses side-illuminated dark-field imaging techniques that essentially detect damage to optical components based on the detector's response to weak signals from the point of damage.At present,the on-line detection technology of dark field imaging damage of side illumination has become mature,but this technology can only detect the damage of optical components after laser irradiation,and can not detect the dynamic damage characteristics during laser irradiation,such as the damage bursting force of glass-lined glass.Learning characteristics,B-point growth characteristics,etc.Such kinetic damage characteristics can only be detected using nonlinear techniques.In this thesis,the optical component damage detection technology based on optical parametric amplifier(OPA)is explored.The phase matching relationship and effective gain of nonlinear crystal are calculated theoretically.The relevant parameters affecting the optical parametric amplification process are analyzed.The linear crystal was optimized.The KDP crystal is used to amplify the scattered light generated by the damage of the optical element under the intense laser irradiation as the seed light source,and the effective gain of 103 is obtained.The image collected by the CCD can observe about 30?m on the optical element to be tested.The size of the damage point.The effect of crystal attitude,incident beam state and so on the optical amplification characteristics of the seed is studied and calculated.A non-collinear 90°I ooe phase matching method is used to design an easy-to-adjust OPA amplification system.The OPA amplification is realized in the angular range,and the OPA output peak can be obtained at the symmetric position on both sides of the central angle.However,as the angle of the incident light angle changes,the OPA output peak is more sensitive with the crystal attitude adjustment.The effects of different damage morphologies on seed light were analyzed and compared.By selecting the damage depths and the damage points of different damage widths to the OPA,it was observed that the output energy after OPA was detected as the single damage morphology decreased.It also reduces the experimental phenomenon.The data collected by the CCD is processed by the radiation calibration procedure,and the measurement error between the processing result and the actual measured value of the damage point is less than 25%.This OPA optical component damage detection technology can effectively detect the damage points on the optical components,which lays a foundation for the next step in the study of optical component damage dynamics.